Modern charge-coupled devices and other photosensitive semiconductor devices (hereinafter "solid state image sensors") are capable of providing signals representing images formed (focused) on a surface thereof. Generally, the surface of a solid state image sensor is provided with an array (for example, rows and columns) of discrete photosensitive semiconductor elements (for example gates or junctions), and particular array locations correspond to a particular "pixel" (or position) in the image. Modern video cameras, for example, use discrete lens systems (optics) to focus images onto such solid state image sensors.
Generally, a single "taking" lens is supported at a fixed distance, such as at least several or tens of millimeters, from the array of photosensitive elements, so that an image may be focused onto the array. The array is located at the focal plane of the lens. Additional lenses, in front of the taking lens, provide for focusing and image enlargement.
Binary (diffractive) optical elements are discussed in "Binary Optics", Scientific American, May, 1992, pages 92, 94-97 ("Article"), incorporated by reference herein.
U.S. Pat. No. 4,425,501 discloses a transparent member 20 upon which a plurality of lenslets have been formed. The member is "mounted above" the die 10. Each lenslet is associated with a pair of detectors on the die.
U.S. Pat. No. 4,553,035 discloses in FIG. 3A two one-dimensional arrays 21 of photodetectors juxtaposed to a cylindrical lens 21. Also, as shown in FIG. 14, three rows of one-dimensional sensors may be provided, and red (R), green (G) and blue (B) filters may be installed, whereby signals of each sensor may be independently read to obtain color information.
U.S. Pat. No 4,636,631 discloses a lens 8 assembled to a wafer 2 on a substrate, with thickness-calibrating shims 6,7 and with a layer of photoresist 5.
U.S. Pat. No. 4,733,096 discloses in FIG. 2 a lens structure ("sensor substrate" 32; 32a, 32b, 38). An insulating layer 42 is juxtaposed with the lens structure 32. Sensors 44 are juxtaposed with the insulating layer 42.